One obvious concern with a hot tub or heated swimming pool is heating of the water prior to use. If a conventional electrical or fossil-fuel fired heater is used, the cost of keeping the hot tub continuously heated can become exhorbitant. Alternatively, the tub may be kept cold or at a low temerature during times when it is not in use. However, the tub must then be heated to operating temperature before the owner can use it and the warm-up time can be considerable if the tub is of large capacity.
In order to save energy, prior art heating devices have been developed which utilize heat from a hot water source that is continuously kept at an elevated temperature for other reasons, such as furnace burners or home water heaters. An energy savings can be realized because, operating alone, these heat sources are typically not more than approximately 60 percent efficient. The low efficiency is mainly due to heat losses caused by maintaining the water hot for immediate use.
To recapture some of the heat which would ordinarily be lost, some prior art hot tub heating devices circulate the hot water from a space heating or hot water system through sealed heating coils inside the hot tub or pool by means of a pump controlled by a thermostat.
One problem with these prior art systems is that when they are used with a potable hot water heating system they generally do not meet existing plumbing codes. The problem with plumbing codes occurs because a failure in the heat exchanger element located in the hot tub can cause an intermixing of potable water and hot tub water resulting in the potable water becoming contaminated.
Another problem is that conventional heating systems utilize the existing hot tub water circulation system to circulate water through the heater. Generally, known heaters are controlled by a low-pressure safety switch which turns off the heater during a low water pressure condition to prevent damage to the heater and to prevent a fire from an overheated heater. During the normal operation of a hot tub, the conventional filtration system slowly becomes filled. If the user allows the filter to become clogged, thereby reducing the circulation water pressure, then often the heater will shut off resulting in the user placing a service call.
It is, therefore, an object of the present invention to provide a hot tub heating system which meets plumbing codes.
It is another object of the present invention to provide a hot tub heating system which can utilize heat from an existing potable hot water supply and prevent intermixing of the hot tub water and the potable water upon a failure of the heat exchanger.
It is yet another object of the present invention to provide a hot tub heating system which is simple and easy to install.
It is yet another object of the present invention to provide a hot tub heating system which can be easily retro-fitted to existing space heating or potable hot water supplies.
It is still another object of the present invention to provide a hot water heating system which utilizes readily available parts and components.
It is still a further object of the present invention to provide a hot water heating system which requires no special electrical or gas connections and which does not require an exhaust gas flue or stack.
It is another object of the present invention to provide a hot water heating system which does not shut off if the hot tub filter becomes clogged.